Can 2021 MacBook Pro be permanently set to have display brightness of 1000 nits?

Solution 1:

No, as display systems are designed to prevent potentially damaging screen states from occurring which is what a permanent 1000 nit setting would do the screen. This could be embedded within unalterable firmware or somewhere deep in the OS, or somewhere else, but in any case belongs to the category of things that are not user changeable.

The same behaviour occurs with the latest 12.9 iPad Pro.

Theoretically it can be overriden if you can modify the firmware, or the display controller, directly but that’s probably not what you meant as that would require tearing down your laptop and reverse engineering.

For reference, displays that are designed to sustain 1000 nits, or higher, are typically thicker and have active cooling systems such as outdoor displays, commercial video walls, or Apple’s own XDR display.